Asymmetric Diels-Alder Reaction of 1-Methoxybuta-1,3-diene with (2R)-N-Glyoxyloylbornane-10,2-sultam

Starting from sultam 1 , the chiral dienophile (2R)-N-glyoxyloylbornane-10,2-sultam ( 4 ) was readily prepared. Non-catalyzed atmospheric- and high-pressure as well as Eu(fod)₃]-promoted 4 + 2] cycloadditions of 1-methoxy-buta-1,3-diene ( 5 ) to chiral dienophile 4 , leading with high asymmetric induction to 6-methoxy-3,6-dihydro-2H-pyran-2-yl derivatives 6 – 9 , are described. The extent and direction of asymmetric induction in these reactions were established by ¹H-NMR analysis and chemical correlation, respectively. Stereochemical models for both non-catalyzed and Eu(fod)₃]-promoted reactions are proposed.